102 research outputs found
Electrophysiology and neuropharmacology of noradrenergic projections to rat PVN magnocellular neurons
Recommended from our members
Comparative transient analysis of metal and oxide fueled LMFBR. [Loop-type and pool-type designs]
The neutronics and thermodynamics of an LMFBR primary system have been simulated using the DSNP simulation language. A detailed fuel pin and its subchannel model were developed and included in the DSNP library. This permits the reactor core to be simulated with any number of pins having any number of radial and axial nodes. The metal fueled core transients were compared to transients of an oxide fueled core, the conclusion being that for the same perturbations the temperature transients are faster in the metal core. A comparison between pool-type and loop-type reactors was also performed, leading to a conclusion that the transients in the upper plenum temperatures are much slower in the pool-type reactor than in the loop-type reactor
A Three-Level Amplitude Discriminator for the Separation of Multi-Unit Electrophysiological Information
Recommended from our members
Identification of stimulatory and inhibitory inputs to the hypothalamic-pituitary-adrenal axis during hypoglycaemia or transport in ewes
This study used the novel approach of statistical modelling to investigate the control of hypothalamic-pituitary-adrenal (HPA) axis and quantify temporal relationships between hormones. Two experimental paradigms were chosen, insulin-induced hypoglycaemia and 2 h transport, to assess differences in control between noncognitive and cognitive stimuli. Vasopressin and corticotropin-releasing hormone (CRH) were measured in hypophysial portal plasma, and adrenocorticotropin hormone (ACTH) and cortisol in jugular plasma of conscious sheep, and deconvolution analysis was used to calculate secretory rates, before modelling. During hypoglycaemia, the relationship between plasma glucose and vasopressin or CRH was best described by log(10) transforming variables (i.e. a positive power-curve relationship). A negative-feedback relationship with log(10) cortisol concentration 2 h previously was detected. Analysis of the 'transport' stimulus suggested that the strength of the perceived stimulus decreased over time after accounting for cortisol facilitation and negative-feedback. The time course of vasopressin and CRH responses to each stimulus were different However, at the pituitary level, the data suggested that log(10) ACTH secretion rate was related to log(10) vasopressin and CRH concentrations with very similar regression coefficients and an identical ratio of actions (2.3 : 1) for both stimuli. Similar magnitude negative-feedback effects of log(10) cortisol at -110 min (hypoglycaemia) or -40 min (transport) were detected, and both models contained a stimulatory relationship with cortisol at 0 min (facilitation). At adrenal gland level, cortisol secretory rates were related to simultaneously measured untransformed ACTH concentration but the regression coefficient for the hypoglycaemia model was 2.5-fold greater than for transport. No individual sustained maximum cortisol secretion for longer than 20 min during hypoglycaemia and 40 min during transport. These unique models demonstrate that corticosteroid negative-feedback is a significant control mechanism at both the pituitary and hypothalamus. The amplitude of HPA response may be related to stimulus intensity and corticosteroid negative-feedback, while duration depended on feedback alone
Reduction of Delayed-Neutron Contribution to Variance-to-Mean Ratio by Application of Difference Filter Technique
- …